package com.atguigu.practice;

import java.util.LinkedList;
import java.util.Queue;

public class BinaryTree {
    public static int size; //节点个数
    //获取叶子节点的个数  遍历思路
    public static int leafSize = 0;
    public TreeNode root;

    //创建一颗二叉树,并返回其根节点
    public TreeNode createTree() {
        TreeNode A = new TreeNode('A');
        TreeNode B = new TreeNode('B');
        TreeNode C = new TreeNode('C');
        TreeNode D = new TreeNode('D');
        TreeNode E = new TreeNode('E');
        TreeNode F = new TreeNode('F');
        TreeNode G = new TreeNode('G');
        TreeNode H = new TreeNode('H');
        A.left = B;
        A.right = C;
        B.left = D;
        B.right = E;
        C.left = F;
        C.right = G;
        D.left = H;
        this.root = A;
        return root;
    }

    //前序遍历
    public void preOrder(TreeNode root) {
        if (root == null) return;
        System.out.print(root.val + " ");
        preOrder(root.left);
        preOrder(root.right);
    }

    //中序遍历
    public void inOrder(TreeNode root) {
        if (root == null) return;
        inOrder(root.left);
        System.out.print(root.val + " ");
        inOrder(root.right);
    }

    //后序遍历
    public void postOrder(TreeNode root) {
        if (root == null) return;
        postOrder(root.left);
        postOrder(root.right);
        System.out.print(root.val + " ");
    }

    //获取节点个数,遍历思路
    public void size(TreeNode root) {
        if (root == null) size = 0;
        size++;
        size(root.left);
        size(root.right);
    }

    //获取节点个数
    public int size2(TreeNode root) {
        if (root == null) return 0;
        return size2(root.left) + size2(root.right) + 1;
    }

    public void getLeafSizeCount(TreeNode root) {
        if (root == null) return;
        if (root.left == null && root.right == null) {
            leafSize++;
        }
        getLeafSizeCount(root.left);
        getLeafSizeCount(root.right);
    }

    //获取叶子节点个数
    public int getLeafSizeCount2(TreeNode root) {
        if (root == null) return 0;
        if (root.left == null && root.right == null) {
            return 1;
        }
        return getLeafSizeCount2(root.left) + getLeafSizeCount2(root.right);
    }

    //获取第k层节点个数
    public int getKLevelCount(TreeNode root, int k) {
        if (root == null) {
            return 0;
        }
        if (k == 1) {
            return 1;
        }
        return getKLevelCount(root.left, k - 1) + getKLevelCount(root.right, k - 1);
    }

    //获取二叉树的高度  时间复杂度O(N)
    public int getHeight(TreeNode root) {
        if (root == null) return 0;
        return getHeight(root.right) > getHeight(root.left) ? getHeight(root.right) + 1 : getHeight(root.left) + 1;
    }

    //检测值为value的是否存在
    public TreeNode find(TreeNode root, char val) {
        if (root == null) return null;
        if (root.val == val) {
            return root;
        }
        TreeNode ret1 = find(root.left, val);
        if (ret1 != null) return ret1;
        TreeNode ret2 = find(root.right, val);
        if (ret2 != null) return ret2;
        return null;
    }

    // 层序遍历   利用队列来进行
    public void levelOrder(TreeNode root){
        if(root==null) return;
        Queue<TreeNode> queue=new LinkedList<>();
        queue.offer(root);
        while(!queue.isEmpty()){
            TreeNode cur=queue.poll();
            System.out.print(cur.val+" ");
            if(cur.left!=null){
                queue.offer(cur.left);
            }
            if(cur.right!=null){
                queue.offer(cur.right);
            }
        }
    }

    //判断一棵树是不是完全二叉树
    public boolean isCompleteTree(TreeNode root){
        if(root==null) return true;
        Queue<TreeNode> queue=new LinkedList<>();
        queue.offer(root);
        while(!queue.isEmpty()){
            TreeNode cur=queue.poll();
            if(cur!=null){
                queue.offer(cur.left);
                queue.offer(cur.right);
            }else{
                break;
            }
        }
        while(!queue.isEmpty()){
            TreeNode cur=queue.peek();
            if(cur!=null){
                return false;
            }else{
                queue.poll();
            }
        }
        return true;
    }

    //节点
    static class TreeNode {
        public char val;
        public TreeNode left;
        public TreeNode right;

        public TreeNode(char val) {
            this.val = val;
        }
    }
}
